The Oghma Infinium (Plural: Oghmas Infinium[1]) is a very powerful Daedric artifact of the Daedric Prince, Hermaeus Mora. It is an ancient tome of knowledge written by Xarxes, the wizard sage and scribe also known as "The Ageless One." The Oghma Infinium is given to Hermaeus Mora's champion upon completion of a specific task or quest. Once read, it disappears, returning to Hermaeus Mora's realm in Oblivion.
The cover of the book is made from the skin of the different Elf races: green for Orsimer, tan for Bosmer, dark/cloudy for Falmer, yellow for Altmer and darkest gray for Dunmer. Upon closer inspection, there are in fact six pieces (the tiny dark scrap on the upper left, above the yellow Altmer hide, presumably the skin of a Dwemer).
The Oghma Infinium is obtained through the quest Discerning the Transmundane given by Septimus Signus, who is found north of the College of Winterhold, at Septimus Signus's Outpost. The quest will only be offered to a Dragonborn of at least level 15 or higher. However, the quest can't be started up until the Runed Lexicon is returned to Septimus; if the Dragonborn is under level 15, Septimus will then say that he needs time to decipher the meaning of the Lexicon. The Dragonborn will then have to wait until they are level 15 before receiving a letter from a courier, telling them that Septimus has deciphered the Lexicon and wants them to return to him.
A locked Dwemer box must be opened by collecting the blood from each of the races of Mer. This includes: Orsimer, Bosmer, Dunmer, Altmer, and Falmer. This blood mixture will approximate the blood of the Dwemer, and provides access to the Dwemer puzzle box.
Skill levels attained from using this book contribute towards level gain as if the skills had been attained by any of the other regular means.
Using the book before acquiring all Daedric Artifacts will not break the Oblivion Walker achievement. It will still count toward the 15 required.
This book does not count as a "skill book," therefore, it does not contribute to the Reader achievement/trophy.
In Gaelic mythology, Oghma (along with his sister Brighid) is one of the twin gods of wisdom and enlightenment. He specifically rules over literature and poetry.
May be a reference to the literary "Book of Sands" by Jorges Luis Borges, a fictional tome with seemingly infinite pages, without a beginning or ending. In the short story the book had characters that were completely incomprehensible and page numbers that constantly changed.
PS3 If at least one skill tree in a desired path is not able to get five skill points, the book may not have any effect in its intended use. Attempting again with a different choice in path seems to work without this issue, but it is still unclear if the first path choice can still be used. (Proved not to happen with the latest patch and all three DLCs included, instead skill just leveled up to 100 and all others leveled up as normal.)